Chapter 1
Manipulating and Checking Values
Section 3
Character Is a Number
Prior to Swift 5, checking if a character is a number is tedious, with a three steps approach. First, the character is casted to a String, and then the String is casted to an Int, and only if the Int is not a nil value, we can be certain that the character is a number, because the three steps method was a success. However, the code is error prone, and not as robust as the new Swift 5 approach.